Include app hibernation OWNERS file in others

Point all OWNERS lists to the one in
core/java/android/apphiberation/OWNERS so it's easier to maintain. Also
go ahead and add an OWNERS file and directory for tests.

Bug: 175829330
Test: builds
Change-Id: I4eea4658cfce2d23a44030368ba9a41b35ca4d5b
2 files changed